(!!!!!) (Best Single 1963) CV492=12AX7 Mullard UK NOS 1963 (161 series) (1.3/1.3ma) 1% section balance
(!!!!) (Best Value used) ECC83=12AX7 Fisher Mullard ribbed plates used/good 1964 (.8/1.2mA Gm=1400/1600)
(!!!) (Good Value Single) 12AX7=ECC83 Mullard GE UK ribbed plates used/good 1966 (.8/.9ma and Gm=1450/1600)
(!!!) (Recommended Single 1962) ECC83=12AX7 Mullard Webcor ribbed plates used/very good 1962 (161 series) in white box (1.0/1.1ma and Gm=1600/1600)
(!!!) (Recommended Single) ECC83=12AX7 Mullard Webcor ribbed plates used/good 1962 (161 series) in white box (1.0/0.7ma and Gm=1600/1400)
